Security tip for vascular catheter and method of using same

ABSTRACT

A catheter ( 100 ) having a first lumen ( 110 ) having a first distal tip ( 112 ) and a second lumen ( 130 ) having a second distal tip ( 132 ). The first and second distal tips ( 112,132 ) include openable portions that are normally closed when undeflected by lumen fluid pressure imbalance relative to the blood pressure of the patient. The first lumen ( 110 ) has an openable portion, flap ( 114 ) that opens proximally into the first lumen when the first lumen is under negative pressure to withdraw blood from the vessel through the first lumen to be dialysed (but that can open distally into the vessel under positive lumen pressure to permit blood flow into the vessel). The second lumen ( 130 ) extends distally beyond the first distal tip ( 112 ) to its second distal tip ( 132 ), and its openable portion is several lip sections ( 135 ) that are normally closed against each other when undeflected but that open outwardly when the second lumen is positively pressurized during hemodialysis, permitting blood to return to the patient&#39;s vessel.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority from U.S. Provisional Patent Application Ser. No. 60/679,098 filed May 9, 2005.

FIELD OF THE INVENTION

This relates to the field of medical devices and more particularly to catheters and catheter assemblies.

BACKGROUND OF THE INVENTION

Hemodialysis catheters are implanted into the vasculature of a patient, and have proximal ends that extend from the patient and are connectable to and disconnectable from tubing of a hemodialysis apparatus. Such catheters are provided with a first lumen and a second lumen coextending to respective distal tips that are carefully positioned at a selected site in a particular vessel of the patient, so that undialysed blood may be withdrawn from the patient's vessel while dialysed blood may be reintroduced into the patient's vessel simultaneously, at respective distal tip openings of the lumens. The catheter lumens may be coextending separate catheters or may be dual lumens of a single catheter separated by a septum wall. The distal tips of the two lumens are generally staggered along the vessel such that blood being withdrawn does not include any significant amount of dialysed blood that has been reintroduced into the vessel at the more distal of the two distal tips.

When a particular dialysis procedure has been completed, the proximal ends of the catheter are disconnected from the tubes of the hemodialysis apparatus, and the lumens are generally inactive until the subsequent dialysis procedure, although fluid medication or saline may be infused into at least one of the lumens, if and when desired, or a blood sample withdrawn. However, blood is highly susceptible to coagulation and clot formation. The addition of a specific agent or locking solution to the catheter or any extracorporeal blood-contacting surface can reduce the incidence of coagulation by interfering and/or inhibiting the hematological chemistry of blood and its interaction with synthetic materials, such as those from which catheters are made.

It is conventional, then, to introduce anticoagulant locking solutions such as heparin into an implanted catheter between hemodialysis treatments, to prevent clotting of blood within the catheter, and which then is withdrawn for the subsequent dialysis procedure. The blood pressure of the patient effectively maintains the locking solution within the catheter lumens by producing a pressure gradient against the locking solution, even though the distal lumen tips are open structures. However, certain amounts of locking solution are known to enter the patient's blood stream through the open distal tips. The amounts introduced into the patient are not at a level to cause toxicity or disrupt a patient's hematology.

It is desired to provide a catheter that will minimize or eliminate the small amounts of locking solution entering a patient's blood stream from an implanted catheter between dialysis treatments.

SUMMARY OF THE INVENTION

The catheter of the present invention includes a first lumen having a first distal tip, and a second lumen having a second distal tip, wherein the first and second distal tips having wall sections that are normally disposed in a closed position but are each openable under fluid pressure. While both lumens have openable distal tip wall sections, the first distal tip has a wall section openable both inwardly and outwardly when the first lumen is subjected to negative pressure and positive pressure, respectively, relative to the blood pressure of the patient in whom the catheter has been implanted; but, the second distal tip has a wall section openable only outwardly, that is, when the second lumen is subjected to positive pressure, and that closes when the second lumen is subjected to negative pressure.

In a preferred embodiment, the first lumen includes a flap section that is joined at a connected section to the wall of the first lumen and extends to a free end that extends to the opposite side of the first lumen to close the first distal tip when undeflected; the flap section is deflectable to open into the first lumen under negative pressure applied to the proximal end of the first lumen, and is deflectable to open outwardly from the first lumen under positive pressure applied to the proximal end of the first lumen.

The second lumen extends a selected distance distally of the first distal tip to a second distal tip that is a generally rounded tip when closed, and the second distal tip is defined by an openable section that is internally concave and may be formed by at least one slit cut into a closed rounded distal tip after extrusion of the lumen, defining at least two generally curved lip portions. The several lip portions are openable outwardly under positive pressure applied to the distal end of the second lumen, and a closable together under negative pressure applied to the second lumen. Near the second distal tip, in the side wall of the second lumen are one or more openable side port sections that are openable inwardly upon application of negative pressure to the proximal end of the second lumen.

The closable and openable sections of the first and second distal tip sections of the first and second lumens operate thusly: during hemodialysis, negative pressure is applied to the first lumen and blood is drawn from a patient's vessel into the first distal tip and through the first lumen; positive pressure applied to the second lumen when blood enters the proximal end of the second lumen and separates the several lip portions at the second distal tip to re-enter the vessel. Were the reverse of the pressures to be caused by an incorrect hemodialysis connection, blood traveling into the first lumen would open the flap to enter the vessel, while negative pressure on the second lumen would close the several lip sections but open the side ports for blood to enter from the vessel. Between dialysis procedures, locking solution injected under low pressure into the catheter would fill both lumens since the distal tips would be in their closed, undeflected conditions, and when removed, blood from the vessel would enter both distal tips due to negative pressure on both lumens.

The present invention also includes a method for maintaining a locking fluid in an implanted catheter; comprising the steps of: providing a catheter having a first lumen having a closed openable first distal end and a first proximal end, and a second lumen having a closed openable second distal end and a second proximal end; and injecting locking fluid into the first and second proximal ends, wherein the closed first and second distal ends retain the locking fluid in the first and second lumens. The present invention also includes a method of removing a lock solution from a catheter, comprising the steps of: providing a catheter having a first lumen having a closed openable first distal end and a first proximal end, and a second lumen having a closed second distal end and a second proximal end, and at least one closed openable side port disposed proximal of the second distal end; withdrawing the lock solution from the first proximal end, wherein the first distal end opens to allow blood into the first lumen; and, withdrawing the lock solution from the second proximal end, wherein the at least one flap opens to allow blood into the second lumen

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate the presently preferred embodiments of the invention, and, together with the general description given above and the detailed description given below, serve to explain the features of the invention. In the drawings:

FIG. 1 is a side view, in section, of a distal end of a catheter according to a first embodiment of the present invention;

FIG. 1A is a distal end profile view, in section, of the catheter taken along lines 1A-1A of FIG. 1;

FIG. 2 is an enlarged portion of the catheter taken along oval 2 of FIG. 1;

FIG. 3 is an enlarged distal end profile view, in section, of the catheter being operated in normal operation;

FIG. 4 is an enlarged distal end profile view, in section, of the catheter being operated in reverse operation; and

FIG. 5 is an enlarged distal end profile view, in section, of a catheter according to a second embodiment of the preferred invention.

DETAILED DESCRIPTION OF THE INVENTION

In the drawings, like numerals indicate like elements throughout. Certain terminology is used herein for convenience only and is not to be taken as a limitation on the present invention. The term “distal” in meant to describe the portion of a catheter according to the present invention that is inserted into a patient, and the term “proximal” is meant to describe the portion of a catheter according to the present invention that remains exterior of the patient. The terminology includes words specifically mentioned, derivatives thereof, and words of similar import. The following describes preferred embodiments of the invention. However, it should be understood based on this disclosure, that the invention is not limited by the preferred embodiments described herein.

Referring now to FIG. 1, a catheter 100 according to a first embodiment of the present invention is shown. The catheter 100 is a dual lumen catheter used for hemodialysis, wherein a first lumen 110 is used to draw blood from a vessel, such as the internal jugular vein, and a second lumen 130 is used to return blood to the vessel. Further, while the second lumen 130 is used to return blood to the vessel, the second lumen 130 may also be used to administer other fluids, such as medication, to the vessel.

The inventive aspect of the present invention is the distal end 102 of the catheter 100. Consequently, the proximal end of the catheter 100, which typically includes: a hub at the proximal ends of the first and second lumens 110, 130; a pair of extension tubes extending proximally from the hub, such that each extension tube is in fluid communication with one of the first and second lumens 110, 130 through the hub; and a luer connector on a proximal end of each of the extension tubes, is not shown, as the proximal end of the catheter 100 is known to those skilled in the art.

As seen in FIG. 1A, the first lumen 110 preferably has a D-shaped cross section and the second lumen 130 preferably has a circular cross section. However, those skilled in the art will recognize that the cross sections may be other shapes, such as “Double D”, “Circle C”, or other lumen cross section configurations known to those skilled in the art.

A cross-sectional view of the distal end 102 of the catheter 100 is shown in FIG. 1. The first and second lumens 110, 130 are adjacent to and parallel to each other, and are separated from each other by a septum 104. The second lumen 130 extends more distally than the first lumen 110. The first and second lumens 110, 130 provide a smooth outer surface for insertion into a patient's blood vessel.

The distal end 112 of the first lumen 110 is enlarged in FIG. 2. The distal end 112 includes a flap 114 that extends obliquely from a connected distal portion 116 to a free proximal portion 118. The flap 114 closes the distal end 112 of the first lumen 110 to restrict fluid flow into or out of the first lumen 110. The connected distal portion 116 is sufficiently pliable to allow the flap 114 to pivot about the distal portion 116 to open the first lumen 110 during use, such as when blood is either being drawn into the first lumen 110 or when blood is being expelled from the first lumen 110.

Referring back to FIGS. 1 and 1A, the second lumen 130 includes an internally concave, generally dome-shaped tip or distal end 132 that is generally closed, but with a plurality of slits 134 extending along wall sections of the second distal portion proximally from the distal end, the slits being arranged, for example, as at least one pair of opposed slits generally bisecting the second distal portion and extending proximally from the distal tip 132, whereby bisected or slit-divided portions of the second distal tip are movable apart allowing, the distal end 132 to open under pressure from the second lumen 130 such that the second distal end is a valve. Slits 134 are shown in FIGS. 1 and 1A arranged as two pairs of opposing slits. A generally curved lip portion 135 is formed between each slit 134. As seen in FIG. 1A, four lip portions 135 are formed, although those skilled in the art will recognize that more or less than four lip portions 135 may be formed. The shape of the distal end 132 and the cut of the slits 134 allow fluid flow from the second lumen 130, through the distal end 132 and out of the second lumen 130, but restrict fluid flow into the second lumen 130 from the distal end 132.

A plurality of side ports 136 are formed in the walls of the second lumen 130 proximal of the distal end 132, with a flap 137 covering each side port 136. Each flap 137 is preferably generally bulbous-shaped, with a distal connected end 138 and a free proximal end 140. In an unpressurized condition, each flap 137 closes off its respective side port 136 to restrict fluid flow through the side port 136 by being disposed within the thickness of the wall section. It may also be seen that the second distal end portion, the second distal tip 132 and the second movable portions 135 are formed to be integral with the wall section of the second lumen 130 that has a generally constant thickness.

To manufacture the catheter 100, it is preferred that the lumens 110, 130 are co-extruded according to procedures well known to those skilled in the art. The distal end 102 is inserted into a tipping machine that forms the flap 114 over the distal end 112 of the first lumen 110 and forms the internally concave distal end 132 of the second lumen 130. The flap 114 is then die cut to separate the free end 118 of the flap 114 from the distal end and to allow the flap 114 to rotate about the connected end 116. The slits 134 are also cut to form the lip portions 135 in the distal end 132 of the second lumen 130. The flaps 137 are also die cut to separate the free end 140 of each flap 137 from the wall of the second lumen 130.

In operation, the catheter 100 is inserted into the patient's blood vessel according to techniques well known to those skilled in the art. When the proximal end of the catheter 100 is connected to an exterior device, such as a hemodialysis machine (not shown), blood flows from the vessel, through the catheter 100, to the exterior device, back through the catheter 100, and into the vessel again.

When the catheter 100 is correctly connected to the exterior device, standard operation of the catheter 100 is shown schematically in FIG. 3. Blood is drawn from the vessel V into the distal end 112 of the first lumen 110 along the direction of arrow “A”. Blood pressure acting on the flap 114 pivots the flap 114 about the connected end 116 so that the free end 118 travels generally proximally, opening the distal end 112 and allowing the blood to flow into the first lumen 110. The blood then travels to the exterior device, where the blood is processed.

The processed blood is then transported to the second lumen 130, where the blood enters the proximal end of the second lumen 130 and travels through the second lumen 130 to the distal end 132 of the second lumen 130. The pressure of the flowing blood against the distal end 132 of the second lumen 130 separates the lip portions 135 from each other, opening the distal end 132, and allowing the blood to exit the second lumen 130 along the direction of arrow “B”.

Occasionally, however, the catheter 100 may be incorrectly connected to the exterior device such that blood is drawn into the second lumen 130 and discharged through the first lumen 110. Operation of the catheter 100 in this manner is shown schematically in FIG. 4. Blood is drawn into the vessel V into the second lumen 130 through the flaps 137 in the distal end 132 of the second lumen 130, as shown by the arrows “C” in FIG. 4. The flaps 137 open into the second lumen 130 to allow blood to be drawn from the vessel V into the second lumen 130. The blood then travels to the exterior device, where the blood is processed.

The processed blood is then transported to the first lumen 110, where the blood enters the proximal end of the first lumen 110 and travels through the first lumen 110 to the distal end 112 of the first lumen 110 to the flap 114. Blood pressure acting on the flap 114 pivots the flap 114 about the connected end 116 so that the free end 118 travels generally distally, opening the distal end 112 and allowing the blood to flow back into the vessel V, as indicated by arrow “D”.

In between treatments, when blood is not flowing through the catheter 100, a catheter lock solution is injected into each of the first and second lumens 110, 130 from the proximal end of each of the first and second lumens 110, 130. Regarding the first lumen 110, the flap 114 biases toward the closed position to close the distal end 112 of the first lumen 110 and prevent the lock solution from dispersing from the first lumen 110 into the vessel V. Regarding the second lumen 130, the lip portions 135 bias toward a closed position to close the distal end 132, and the flaps 137 bias toward the wall of the second lumen 130 to close the flaps 137 to prevent the lock solution from dispersing from the second lumen 130 into the vessel V.

To prepare the catheter 100 for a subsequent treatment, a syringe (not shown) is connected to the proximal end of the first lumen 110 and the lock solution is vacuum drawn from the first lumen 110 into the syringes. The flap 114 biases toward the open position to allow blood into the distal end 112 of the first lumen 110 to make up for the now-depleted lock solution. The syringe (or a subsequent syringe) is connected to the proximal end of the second lumen 130 and the lock solution is vacuum drawn from the second lumen 130 into the syringe. The flaps 137 open to allow blood into the distal end 132 of the second lumen 130 to make up for the now-depleted lock solution. The syringe is removed and the proximal end of the catheter 100 is able to be connected to a hemodialysis machine.

In an alternate embodiment, shown in FIG. 5, a catheter 200 includes a first lumen 210 and a second lumen 230 that have distal ends 212, 232, respectively, that are split apart from each other. A septum 204 that divides the first lumen 210 from the second lumen 230 splits off at a predetermined location to allow the distal end 212 of the first lumen 210 to separate from the distal end 232 of the second lumen 230.

Optionally, as will be recognized by those skilled in the art, the septum 204 may be splittable such as by being constructed to have two layers initially joined to each other as shown in FIG. 5, to allow the distal end 212 of the first lumen 210 to be split away from the distal end 232 of the second lumen 230 at a variable location, as determined by the inserting physician during insertion of the catheter into the patient.

It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims. 

1. A catheter comprising: a first conduit defining a first lumen having a first proximal end and a first distal end portion concluding in a first distal tip; a second conduit defining a second lumen having a second proximal end and a second distal end portion concluding in a second distal tip extending distally beyond the first distal tip and having a generally circular cross section, wherein the second distal tip comprises a generally internally concave portion having formed therein at least two slits together bisecting the second distal tip and wall sections thereof, the slits extending proximally from the second distal tip for a selected length, whereby the slit-divided portions of the second distal tip are movable apart; and a septum separating the first and second lumens, wherein wall sections of the first and second distal tips define respective first and second valves that are normally closed and are openable in response to relative pressure imbalances inside and outside the respective first and second lumens, but wherein the second valve only opens outwardly, under positive pressure inside the second lumen.
 2. The catheter according to claim 1, wherein the first valve comprises a flap having a connected distal portion and a free proximal portion.
 3. The catheter according to claim 1, wherein the first distal end portion has a generally D-shaped cross section.
 4. The catheter according to claim 1, wherein the second conduit further comprises at least one side port having open and closed positions, and fluidly communicating the second lumen with an exterior of the second conduit when in the open position.
 5. The catheter according to claim 4, wherein the at least one side port is longitudinally disposed between the first distal tip and the second distal tip.
 6. The catheter according to claim 4, wherein the at least one side port comprises a flap having a connected distal end and a free proximal end.
 7. The catheter according to claim 1, wherein the distal end portion of the first lumen and the distal end portion of the second lumen are joined to each other in such a manner as to be splittable from each other.
 8. The catheter according to claim 1, wherein the distal end portion of the first lumen and the distal end portion of the second lumen are split from each other.
 9. A catheter assembly comprising: a first lumen having a first distal end with a first movable portion to at least partially close the first distal end; and a second lumen having a second distal end extending distally beyond the first distal end to a generally dome-shaped tip defining a second movable portion to at least partially close the second distal end, wherein the second movable portion comprises a generally internally concave portion having at least two slits together bisecting the second distal end and the generally dome-shaped tip thereof and extending proximally therefrom for a selected length whereby slit-divided portions of the second distal end are movable apart, wherein, when the catheter assembly is in use, fluid flow through the first lumen opens the first movable portion and fluid flow through the second lumen opens the second movable portion allowing fluid out of the first and second lumens, respectively, and wherein the first movable portion is openable to allow fluid into the first lumen but the second movable portion is not openable to allow fluid into the second lumen.
 10. The catheter assembly according to claim 9, wherein the first movable portion differs from the second movable portion in shape and structure.
 11. The catheter assembly according to claim 9, wherein the second lumen further comprises at least one normally closed flap longitudinally disposed between the first distal end and the second distal end, each flap having a connected distal end and a free proximal end and openable at least inwardly.
 12. The catheter according to claim 1, wherein the second distal tip is generally dome-shaped and comprises two pairs of slits formed therein and extend proximally therefrom and within respective planes that generally intersect the longitudinal axis at right angles.
 13. The catheter according to claim 6, wherein the flap is formed from and integral with the wall section defining the second conduit, and is disposed within a complementarily shaped cut-out in the wall section when not open.
 14. The catheter assembly according to claim 9, wherein at least the second distal end and generally dome-shaped tip and second movable portions are formed from and are monolithic with a wall section of the second lumen that has a generally constant thickness therealong.
 15. The catheter according to claim 1, wherein at least the second distal end portion and second distal tip and second valve are formed from and are monolithic with a wall section of the second lumen that has a generally constant thickness therealong. 